Moisture tester



3,005,152 Patented Oct. 17, 1961 3,005,152 MOISTURE TESTER .Edwin J. Jennings, In, Ponca City, Okla, and John A.

Reddick and Earl E. Berkley, Houston, Tex., assignors to Anderson, Clayton 8: Company, Houston, Tex., a

corporation of Delaware Filed Apr. 8, 1957, Ser. No. 651,473 4 Claims. (Cl. 324-65) This invention relates to an apparatus for determining the percentage moisture content of fibrous material and more particularly to an apparatus for determining such moisture content by relating it to the electrical direct current resistance of the fibrous material. The moisture content of fibrous, granulated, and comminuted material and seeds is important in many instances. For example, cotton is traded on a weight basis and therefore its moisture content needs to be known and controlled. With cotton its moisture content affects ginning results. High moisture in the cotton seed in seed cotton will cause a free fatty acid rise and a subsequent high refining loss.

It is old in the art to compress a sample of cotton or other fiber, determine the electrical direct current re sistance of the fiber so compressed, and compare this resistance with a curve plotting direct current electrical resistance against percentage moisture content to determine the percentage of moisture in the cotton. The devices in use now have several objectionable features with the principal one being the amount of time required for making a test. Any reduction in the time necessary to conduct a test reduces the labor costs and in many instances give more accurate results in that often the fiber sample, such as lint cotton, taken from a bin will change its moisture content by the time the test is completed, because of the time required to conduct a test.

It is therefore a general object of the present invention to. provide an apparatus for quickly determining the moisture content of material such as fibrous, granulated, and comminuted material and seeds.

Another object of the present invention is to provide an apparatus for determining moisture content of such material which apparatus utilizes a direct current electrical resistance meter to indicate directly the percentage moisture content of the sample being tested.

A further object is to provide such a moisture testing apparatus inwhich the test sample may be placed under controlled pressure by a fluid pressure means.

Yet a further. object of the present invention is to provide such an apparatus which is easily portable and yet has a test chamber of large size to test a more representative sample. I A still further object of the present invention is to provide such an apparatus which is rugged, easy to use, and economical to maintain. n Other and further objects, features, and advantages of the present invention will appear as the description of the preferred example of the invention proceeds, which is given for the purpose of disclosure and which is taken in conjunction with the accompanying drawings, where like character references designate like parts throughout the several views and where,

FIGURE 1 is a schematic drawing of the present invention illustrating the fluid pressure and electrical circ i s FIGURE 2 is a plan view of the present. invention,

FIGURE 3 is a side elevation illustrating the present invention, and FIGURE 4 is a cross sectional View taken along the line 4-e4 of FIGURE 2.

- Referring to the drawings, and particularly to FIGURE moisture tester of the 2 2, the moisture tester as a whole includes a test chamber 10 in which a fibrous sample is compressed by a hydraulic system indicated generally by the numeral 12 during which time the direct current electrical resistance of the compressed sample is indicated by a resistance meter 14.

As best seen in FIGURES 3 and 4, the test chamber 10 is preferably cylindrical in shape and has the outer case 16 of aluminum to give a light Weight but sturdy construction. At the right end of the test chamber 10 as viewed in FIGURE 4 is the fixed circular plate 18 of electrically conductive material, preferably copper, which plate 18 is electrically insulated from the outer case 16 by the liner 20 of transparent acrylic plastic known as Plexiglas or of other insulating material. The Plexiglas liner 20 is counterbored at its right end to provide a shoulder 22 against which the fixed plate 18 abuts preventing any movement of this fixed plate to the left. Backing the fixed plate 18 is an insulating disk 24 held in position by an end plate 26 of the outer case 16 which is threadedly secured into the right end of the outer case 16 such as by the complementary threads .28. As thus constructed the fixed plate 18 is electrically insulated from the test chamber 10 except for its exposed inner face.

Parallel to and located to the left of the fixed plate 18 as Viewed in FIGURE 4 is the movable electrically conductive plate 30 preferably made of brass for good electrical contact with the sample. This movable plate 30 conforms to the inner walls of the Plexiglas liner 2t) and may be advanced toward and retracted from the fixed plate 18 along the axis of the test chamber 10 to compress a sample between these plates 18 and 30.

Closing the left end of the test chamber 10 as viewed in FIGURE 4 is an end plate 3-2 secured in the outer case 16 in any conventional manner such as by welding. To advance and retract the movable plate 30 a piston rod 34 in its housing 36slidably extends through an opening 42 in the end plate 32 and is secured to the movable plate 30 such as by the threaded nut 38 welded to the back side of the movable plate 30 and by the locking nut 40. The housing 36 is held in place by the bolts 46 into the end plate 32.

For the purpose which will be made clear later herein, a flexible electrical lead 48 is electrically connected to the movable plate 3ll by the terminal screw 50 and to the end plate 32 by one of the bolts 46. Also, an electrical lead 52 is electrically connected to the fixed plate 18 through the end plate 26 and insulating'disk 24 at the other end of the test chamber 10 which lead 52 is electrically shielded from the end plate 26 such as by this lead 52 being a shieldedwire and the use of an insulating insert 54 in the opening 56 through the end plate 26. r

Referring now to FIGURES .1 and 2 there is best illustrated the fluid pressure system, here shown as the hydraulic system 12 which advances and retracts the movable. plate 30 for compressing the test sample. This hydraulic system includes the piston and cylinder unit 58 to which hydraulic force of controlled direction and magnitude is appliedby the hydraulic pump and control unit 60 through tubingGZ. The piston and cylinder unit 58 is of any conventional design and includes a double acting piston 64-,within the cylinder 66 so that when fluid pressureis applied to .the left end of the cylinder 66 as viewed in FIGURE 1 and drains from the right end, the piston 64 moves to the right pushing the piston rod 34 and movable plate 30 to the right advancing the movable plate 30 toward the fixed plate 18. A reversal flow of fluid force moves the piston 64 to the left retracting the movable plate 30.

The pump and control unit '60 may be any of several commercial assemblies which control both the amount and direction of fluid force moving through the tubes 62 to the cylinder 66 and which units are readily available on the market. In the preferred example an Electrol 430 Powerpak manufactured by the Electrol Hydraulics Incorporated of Kingston, NY. is quite satisfastory. As best seen in FIGURES 2 and 3 the means to develop the amount of fluid force of the particular pump control 60 includes the pivoted pump handle 68 and the means to control the direction of the fluid force through the tubes 62 includes the pivoted selector lever 70. As each test should be conducted under the same amount of pressure on the sample the pump and control unit 60 preferably also contains an adjustable relief valve to prevent an excess of pressure on the drive side of the piston 64. In this particular control and pump unit 60 this relief valve is located under the fill plug 69 Where it may be adjusted to the desired line pressure. As this pump and control unit 60 and other satisfactory ones are readily available on the open market, no further description of them is necessary or appropriate. To indicate the pressure on the drive side of the piston 64 a pressure gauge 71 is placed in the tube 62 leading to the left end of cylinder 66 as viewed in FIGURES l and 2.

Referring now to FIGURES 1 and 4, the electrical circuit to measure the direct current resistance of the fibrous sample compressed between plates 30 and 18 includes the resistance meter 14 connected to the 110 volt A.C. supply and connected in series to the fixed plate 18 through the lead 52 from one terminal post of the resistance meter 14 and to the movable plate 30 through a lead 72 connected at one end to another terminal post on the resistance meter 14 and at the other end to the movable plate 30 through the flexible lead 48 and a bolt 46. The resistance meter 14 converts the alternating current supply to direct current flow through the test sample. The resistance meter may be of any several standard types commercially available on the market such as S.I.E. Model C-6 Resistance Meter manufactured by Southwestern Industrial Electronics C0., PO. Box 13085, Houston 19, Tex. As thus connected the resistance meter 14 will measure the resistance to electrical flow between the plates 30 and 18 and of the sample compressed there between. In order that the resistance meter 14 will indicate directly the percentage of moisture of the sample being tested rather than its electrical resistance, a face plate 74 is inserted in the resistance meter 14 reading directly in moisture percentages rather than in ohms electrical resistance. This face plate 74 is prepared from a curve of the electrical direct current resistance of the material being tested plotted against the known moisture percentage content of the material. In the case of use in testing cotton the known moisture content is preferably determined by determining the weight difference of the tested sample before and after heating it for an hour and a half in an oven at 105 to 110 degrees centigrade. As most resistance meters utilize a selector knob such as the knob 76 in FIGURE 2 to change the resistance range indicated by the needle 78 for the variances of moisture content encountered in the test samples, the face plate 74 utilizes a series of arcs 70 with one being for each resistance range put in operation by the selector knob 76.

To insert a sample in the test chamber 10, an opening 80 (see FIGURE 4) is provided in the top of the test chamber through the outer case 16 and the Plexiglas liner 20 in such a position that the opening 80 is between the plates 30 and 18 when the movable plate 30 is in the retracted position illustrated in FIGURE 4. If desired for safety or otherwise a hinged cover 82 of insulating material may be placed over the opening 80 and held in closed position during the test such as by a latch 84.

In orderto hold a test sample of sufiicient size to give a representative sample and in order that the test sample may be quickly inserted and removed from the test chamber 10, the test chamber 10 and the opening are of sufficient size that the operator may insert his hand through the opening 80 to insert and withdraw the sample when the movable plate 30 is in the retracted position shown in FIGURE 4.

For ease of handling and portability the various parts of the moisture tester of the present invention are normally mounted upon a base 88 as best illustrated in FIGURES 2 and 3 which base may be provided with a handle for carrying the entire assembly.

In operation, the 110 volt A.C. supply is turned on to the resistance meter 14 by a toggle switch 86 (FIG- URE 2) to allow the resistance meter 14 to cometo operating condition. A sample of material is then inserted through the opening 80 and into the test chamber 10 between the plates. 30 and 18 then in the position illustrated in FIGURE 4. The relief valve of the control and pump unit 60 having been previously set at thedesired pressure, the selector lever 70 is placed in position to move the piston 64 to the right and pressure is applied to the left end of cylinder 66 by operating the pump handle 68 until pressure on the pressure gauge 71 reaches the desired reading for pressure in the test chamber. 10. If the selector knob 76 of the resistance meter 14 is set for the proper resistance range the needle 78-will show the percentage of moisture content of the material at the time the pressure in the test chamber 10 reaches the desired point as indicated by the pressure gauge 71. If the selector knob 76 is not set for the proper resistance range, then it is turned until a movement of needle 78 occurs which almost instantaneously indicates the per-. centage moisture content of the sample. The selector lever 70 is then moved for reversal of direction of flow of fluid force into cylinder 66 and further operation of the pump handle 68 retracts the movable plate 30 past the opening 80 as illustrated in FIGURE 4 and the. sample is removed and another sample inserted and com pressed by movement of the selector lever 70 and th pump handle 68.

During the entire period of testing the resistance meter 14 is supplied with alternating current which is converted to direct current and supplied to the plates 18 and 30 without any necessity of this electrical circuit to the plates 30 and 18 being turned on or 01f so that the moisture content is indicated directly and instantaneously upon reaching the desired pressure.

In some instances of high moisture content of the sample it has been found that compression of the sample frees moisture and when this occurs more accurate re-' sults are obtained by turning the moisture tester so that the test cylinder 10 is vertical with the plates 18 and 30 horizontal.

As the direct current electrical resistance of the sam plcs depends upon, among other things, the distance between the plates 30 and 18 and the amount of pressure on the sample, the size of the samples and the pressure are comparatively uniform for the tests conducted. For example, with seed cotton samples weighing to grams are normally tested and with lint cotton samples of 33 to 37 grams are normally used. For each of these cottons it has been found that pressures in the test chamber 10 in excess of forty pounds per square inch give the most reliable tests. 7

The present invention, therefore, is well suited to carry out the objects and attain the advantages mentioned as well as others inherent therein.

While only a single example of the invention has been given for the purposes of illustration, changes in details and rearrangements of parts will suggest themselves to those skilled in the art. Accordingly, it is desired to be limited only by the spirit of the invention as defined by the scope of the appended claims.

What is claimed is;

1. A moisture tester comprising, a test chamber adapted tohold a sample of fibrous material, said test chamber including a sidewall having an opening for inserting and removing a sample, and opposite ends, a first electrically conductive plate in the test chamber approximate one end thereof, a second electrically conductive plate in the test chamber approximately parallel to the first plate, said second plate being movable past the opening toward and away from the first plate, means electrically insulating the plates from each other through the chamber, fluid pressure means selectively advancing the second plate toward and retracting it from the first plate Whereby a sample between the plates is compressed upon such advancing and released upon such retraction, control means in the fluid means controlling the force of compression on the sample, and an electrical circuit including the plates and a direct current electrical resistance meter directly converting the direct current electrical resistance of the compressed sample to percentage moisture content of the sample.

2. A moisture tester comprising a test chamber adapted to hold a sample of material, said test chamber including a sidewall having an opening for inserting and removing a sample and opposite ends; a first electrically conductive plate in the test chamber approximate one end thereof; a second electrically conductive plate in the test chamber approximately parallel to the first plate, said second plate being movable past the opening toward and away from the first plate; means electrically insulating the plates from each other through the chamber; fluid pressure means selectively advancing the second plate toward and retracting it from the first plate whereby a sample between the plates is compressed to at least 40 pounds per square inch pressure upon such advancing and released upon such retracting, said fluid pressure means including a piston and cylinder assembly connected to the second plate, a pump tion with the piston and cylinder assembly, and means to indicate pressure exerted by the second plate; and an electrical circuit including the plates and an electrical resistance meter directly converting the direct current electrical resistance of the compressed sample to percentage moisture content of the sample.

3. A moisture tester comprising a test chamber adapted in fluid communicato hold a sample of material, said test chamber including opposite ends and a sidewall having an opening for inserting in and removing a sample, said opening large enough to permit passage of a test sample; a first electrically conductive plate in the test chamber approximate one end thereof, a second electrically conductive plate in the test chamber approximately parallel to the first plate, the second plate being movable past the opening toward and away from the first plate; means electrically insulating the plates from each other through the chamber; fluid pressure means selectively advancing the second plate toward and retracting it from the first plate whereby a sample between the plates is compressed upon such advancing and released upon such retraction, said fluid pressure means including a piston and cylinder assembly connected to the second plate for such movement of the second plate, a pump and control unit in fluid communication with the piston and cylinder assembly, and a pressure gauge adapted to indicate pressure on the compressed sample; and an electrical circuit including the plates and an electrical resistance measuring means adapted to measure the direct current resistance of a compressed sample.

4. The apparatus of claim 3 in which the electrical circuit includes the plates and an electrical resistance meter directly converting the direct current resistance of a compressed sample to its percentage moisture content.

References Cited in the file of this patent UNITED STATES PATENTS 1,826, 247 Heppenstall Oct. 6, 1931 1,890,545 Limbrick Dec. 13, 1932 1,917,241 Dinzl July 11, 1933 2,082,364 Store June 1, 1937 2,343,340 Stevens Mar. 7, 1944 2,469,736 McBrayer May 10, 1949 2,579,316 Hall Dec. 18, 1951 2,622,132 Stocketon Dec. 16, 1952 2,757,334 Potter July 31, 1956 2,813,569 Nelson Nov. 19, 1957 

